The Geek Squad / Poor service

After having an "agent" from The Geek Squad in my home twice and paying almost $500 for his "services and repair" of my computer, my computer still isn't working correctly. I have tried to contact The Geek Squad several times and have been given "the run-around" over and over. At this point I do not know what I can do to correct this problem. One thing I do know, I will not take any future business to The Geek Squad or to Best Buy.